5.81 A cobbler repairs shoes with normal damages for €2 each. The repaired shoes have a distribution with a mean of 60 and a standard deviation of 10.

a. Find the mean daily total revenue earned from the shoes repaired.

b. Find the standard deviation of total revenues from the shoes repaired.

c. Daily costs (in euros) are given by C = 80 + 0.50X where X is the number of shoes repaired. Find the mean and standard deviation of daily profits from daily business.